Secondary batteries may be classified into various types according to the structure of an electrode assembly. Typically, secondary batteries may be classified into a stack-type, a wrapping-type (a jelly-roll type), or a stack/folding type according to the structure of an electrode assembly. The stack-type structure may be obtained by separately stacking electrode units (a cathode, a separator, and an anode) constituting the electrode assembly, and thus an accurate alignment of the electrode assembly is very difficult. In addition, a large number of processes are necessary for the manufacture of the electrode assembly. The stack/folding type structure is generally manufactured by using two lamination apparatuses and one folding apparatus, and thus the manufacture of the electrode assembly is very complicated. Particularly, in the stack/folding type structure, full cells or bi-cells are stacked through folding, and thus the alignment of the full cells or the bi-cells is difficult.
In addition, since the separator may be wound may times by folding, wetting properties of an electrode assembly may be deteriorated.